Gas sampling system



1940. e. L. HASSLER GAS SAMPLING SYSTEM Filed Dec. 20, 1958 2 Sheets-Sheet l lnven ror-z Gerald L. Hdssler Dec. 3, 1940.

G. 1.. HASSLER 2,223,785

GAS SAMPLING SYSTEM xFiled Dec. 20, 1958 2 Sheets-Sheet 2 57 537 60 e5 62 6| 52 55 2o 3 A 5 Fig.7

Invemor: Gerald L- Hassler Patented Dec. 3, 1940 UNITED STATES PATENT OFFICE GAS SAMPLING SYSTEM Application December 20, 1938, Serial No. 246,835

3 Claims.

10 stances, such as oil, in certain formations are derived from the analysis of gases drifting by diffusion upwards to the surface of the ground. It is known that when samples of such gases are collected from a plurality of stations gradually 5 approaching an oil deposit from any direction on the surface of the ground, the amount of gaseous hydrocarbons, and the ratio of ethane and higher hydrocarbons to methane in said soil gases also gradually increases owing to the fact that the higher hydrocarbons diffuse through the soil layers at a slower rate than methane. Since, however, the concentration of the hydrocarbons in the samples obtained is exceedingly small, amounting, for example, to about 3 to 300 parts per million, it is obvious that extremely accurate methods must be used in obtaining, storing and analyzing said soil gases to obtain data of any value from an exploration standpoint.

A suitable method and apparatus for obtaining soil gas samples is described in my application Serial No. 190,473, filed February 14, 1938, and a suitable method and apparatus for analyzing said samples is described in my application Serial No. 237,914, filed October 31, 1938.

The object of the present invention is to provide a suitable storage system for samples of gas obtained underground, said system comprising double-walled containers constructed in such a contamination of the samples due to leakage, diffusion or adsorption phenomena.

It is also the object of this invention to provide a system for delivering gas samples from 45 their sources to said containers and then to the 50 carbon particles.

These and other objects of the invention will be understood from the following description taken with reference to the attached drawings wherein:

55 Fig. 1 is a'diagrammatical side-elevation view manner and of such materials as to avoid the in cross-section of a preferred embodiment of this invention;

Fig. 2 is a front elevation view of the same device drawn to a smaller scale;

Fig. 3 is a plan view of the valve plate 6 shown in Figs. 1 and 2;

Fig. 4 is a flow diagram schematically showing the method of filling the device of Fig. 1 with a sample of underground gas;

Fig. 5 is a flow diagram showing the method of delivering a gas sample held in the device of Fig. l to an analytical apparatus;

Fig. 6 is a diagrammatical elevation view in cross-section of another preferred embodiment of thisinvention; and

Fig. 7 is a flow diagram schematically showing the method of filling the device of Fig. 6 with a sample of underground gas.

Fig. 1 shows diagrammatically and in crosssection one preferred embodiment of the invention, which comprises a double-walled, flexible bag, having an outer envelope 3 and a concentric inner envelope 5. This bag is, made of material having a very small permeability and no tendencies for adsorption or exhalation of hydrocarbon gases. It has been found that Cellophane is especially suitable for this purpose. Cellophane, which is marketed in the form of tubular rolls, may be conveniently cut into tubular sections of any desired length. Two such tubular sections, inserted into one another, have their upper and lower ends clamped between an inner metallic stem l, and an outer metallic member 2, which is bent to a near-annular shape around the stem I, whereby an air-tight fit is insured without the use of any glue, cement or other material capable of contaminating the gaseous contents of the bags by exhalation of impurities.

Both the inner and theouter bags are in communication with the outside by means of a valve structure comprising a metallic plate 6. Openings 1' and TA are drilled through plate 6, and are of an enlarged diameter 8 on the side facing the bag. The walls of the openings 8 are screwthreaded and adapted to receive plugs l 0 and IOA, provided with central passages corresponding to the openings 1 and IA.

A circular hole is punched in the outside wall 3 of the flexible bag and the edges of the wall around said hole are caught in air-tight manner between the plate 6 and. the nut Ill, screwed into opening 8 of said plate. A second hole is punched through bothwalls 3 and 5 of the bag, and the edges of said walls are secured to the plate 6 in the same manner by means of plug IDA.

Plate 6 may be amxed, for example, by means of screw M, to a panel l5, having passages l6 and i1 communicating between the openings 1 and 1A of the plate, and pipes 20 and 20A, or 2| and 2 IA, by means of which gaseous mixtures are forced into the double-walled bag or withdrawn therefrom. Pins 9 and 9A are afi'ixed to the panel |5 in register with the openings 1 and 1A. Allmetallic flap-valves I2 and |2A, having no rubber parts, and requiring no lubrication (either of which might contaminate the sample due to a possible exhalation of hydrocarbons) are held in a normally closed position within passages 1 and 7A between plugs I0 and IBA and the plate 6. When the plate 6 is clamped to the panel l5 by means of screw M, the pins 9 and 3A press against the flap-valves l2 and |2A and open said valves.

In operation, the following procedure may be followed in filling the present bag container with gases obtained underground, and in subsequently delivering said gases to an analytical apparatus.

The container is first attached, by means of plate 6 and screw I4, to the panel I5 in such a manner that the inside of the bag 3 is in communication with pipe 20, and the inside of bag 5 with pipe 23A.

Pipes 20 and 20A form part of a soil gas sampling apparatus such as described in my application Serial No. 190,473,. filed February 14, 1938, pipe 20 leading to a guard ring space between packers 38 and 39 of a probing borehole, and pipe 23A leading to a space 4| from which it is desired to collect the sample, as shown in Fig. 4.

Pipe 29 is provided with a pump 33, and pipe 211A with a pump 34, which are preferably of the auto-pulse metal-bellows type, which do not require any lubrication, whereby contamination of the sample is avoided.

The intake of pump 33 is connected with the pipe 20A by a pipe 35 provided with a valve 32. A valve 3| opens to the atmosphere between the pump 33 and the bag 3.

With valve 32 closed and valve 3| open, both pumps are started, whereby contaminated air is removed from spaces 40 and 4|. Bag 5 expands within the bag 3, which is opento the atmosphere, and forces the air out of said bag 3. After continuing this operation for a desired length of time, valve 3| is closed-and valve 32 is opened. Pump 34 is stopped, only pump 33 continuing to operate, whereby the gas from bag 5 is transferred to bag 3, bag 5 becoming entirely evacuated and collapsing within bag 3. Valve 32 is then closed, valve 3| opened, and the pumping proceeds with both pumps operating until both bags are filled to the desired pressure.

The screw I4 is then unscrewed and the plate 6 removed together with the bag from the panel I5, whereby valves I2 and |2A are automatically closed. The sample obtained in this manner may be left in the present container for a considerable length of time, no contaminations by difiusion of atmospheric air through the elastic partitions being possible, since the space within the inner concentric bag 5, containing the sample to be analyzed, is separated from the atmospheric air by the space within the outer concentric bag 3, filled with substantially the same gaseous mixture as bag 5.

When it is desired to analyze the gas sample, the gas bag is affixed, by means of the plate 6 and a screw MA, to the same or a different panel |5, the bags 3 and 5 being respectively in communication with pipes 2| and 2|A. As shown in Fig. 5, pipe 2| is connected to a pump 33A, having an intake open to the atmosphere, while pipe 2|A, which is provided with a valve 32A, communicates between the inside of the bag 5 and the analytical apparatus schematically shown at 50. By opening valve 32A and pumpin air into the bag 3, the gas sample is forced out of the inner bag into the analytical apparatus. The amount of contamination by diffusion which occurs during this operation due to the presence of atmospheric air in the outer bag 3 is negligible in view of the relatively short duration of said operation.

The containers described above have the advantage of being well suited for operation in the field, being made of resilient material and therefore unbreakable.

Should the operating conditions permit, another preferred type of the present containers may likewise be used, wherein only one of the double walls is made of Cellophane, while the other is made of glass. This type of container is preferable for operation under conditions of a very dry atmosphere, which sometimes may resuit in the cracking and leakage of the double- Walled Cellophane bag.

Referring to Fig. 6, a section of tubular Cellophane 5 is inserted within a glass cylinder 3A, approximately 20 inches long and having a diameter of about 2 inches. The ends are sealed by turning the Cellophane over to the outside to make a tight fit against the fire-polished edges of the glass tube. The space inside the Cellophane is then sealed, at the lower end, by a brass plate 5|, fitting in air-tight fashion over the Cellophane and the glass tube, and, at the upper end, by an additional piece of Cellophane 5A and by a piece of dental dam rubber 53, both Cellophane and rubber being held in airtight fashion against the glass by means of wire 52.

The space within the Cellophane bag communicates with the outside by means of a conduit 54, fitted through plate 5| and the space between the glass and the Cellophane, which is used for the storage of the sample, communicates with the outside by means of a tube 55. By stretching the dental dam rubber 53, and clamping a suitable stopper such as a rubber ball 53, against the orifice of tube 55 on the inner side of container 3A, the gas sample may be, when desired, securely sealed within the space between the glass tube 3A and the Cellophane bag 5.

The tubes 54 and 55 are led into a bushing structure or chamber comprising a rigid metallic or glass tube portion 63 and a rubber tube portion 6|, held together in air-tight fashion by means of wire 62. This bushing is closed at either end in air-tight fashion by stoppers 63 and 34, made of suitable materials such as rubber, tubes 54 and 55 passing through stopper 63, a tube or orifice 23, and a tube 23a, respectively, similar to tubes 20 and 23A of Figs. 4 and 5 passing through stopper 34. Tubes 54 and 55 are provided with nipples 65 and 61, whereby either of said tubes can be put in communication with tube 20A.

Fig. 7 shows the connections diagram used in filling this embodiment of the present gas container with an underground gas sample by means of the apparatus of my application Serial No. 190,473, filed February 14, 1938.

The tube 20, opening to the guard ring space 4!], is connected, by means of a tube 70, with a source of vacuum H, such, for example, as the pumps shown in Figs. 4 and 5 or as a jar partially filled with a liquid and connected by means of a flexible tube hi to another jar 13, the degree of vacuum in jar H being regulated by raising or lowering the jar 13.

With the pipe 28A in the position shown in Fig. '7, that is, with the tube 20A not engaging either nipple $5 or nipple Bl, vacuum is applied to the space within the bushing Ell-45!, emptying both chambers of the container and drawing from the guard ring space 45! and from the sample space t! the air contaminated by contact with the atmosphere. The tube 28A is then connected to the nipple 61, whereby vacuum is applied through the space within bushing (iii-4H to the guard ring space 40 and to the space between the glass tube 3A and the Cellophane 5, causing said Cellophane to adhere to the glass, whereby the Cellophane bag 5 is expanded, and gas from sample space H is drawn thereinto through tube 28A, nipple El and pipe 54. The tube 29A is then disconnected frorn nipple 61 and connected to nipple 65, which can be easily effected by slightly stretching and twisting the elastic part 6| of the bushing. Vacuum is now applied through tubes 10, bushing 6iJ-6l, and tube 54, to the space within the Cellophane bag 5, causing said bag to collapse within the glass tube 3A, whereby the gas from the sample space 4| is drawn into the space between the glass and the Cellophane. It will be noted that during the operation of drawing the sample to said space, a higher vacuum is being applied to the guard ring space 40, according to the teachings of my application Serial No. 190,473, filed February 14:, 1938. This is due to the fact that the guard ring space 4!] is directly in communication with the source of vacuum by means of tubes 10 and 2t, while the sample space 4| is indirectly in communication with the source of vacuum by means of tube 25A, nipple 61, tube 54, Cellophane diaphragm 5, tube 55, bushing -6| and tube 10, the additional resistance being sufficient to insure the desired pressure differential.

It will also be noted that with the arrangement described above, any leakage resulting from a break or a faulty connection will always be directed from the gas sample into the atmosphere, and not from the atmosphere to the gas sample, whereby any contamination of the sample is avoided.

I claim as my invention:

1. In a gas sampling system, two concentric envelopes one wholly within the other, said envelopes being sealed from each other and from the atmosphere, at least the inner envelope being made of flexible material, a conduit in communication with the inside of the inner envelope, 2. second conduit in communication with the inside of the outer envelope, and means for selectively applying to the other ends of said conduits a gaseous pressure, whereby either envelope may be filled by applying a vacuum to the other envelope, and may be emptied by applying a positive pressure to the other envelope.

2. In a gas sampling system, two concentric flexible gas-impervious envelopes one wholly within the other, said envelopes being sealed from each other and from the atmosphere, at normally closed valve structure in communication with the inside of the inner envelope, a normally closed valve structure in communication with the inside of the outer envelope, two tubular conduits, means for clamping said tubular conduits in register with said valve structures, members rigidly affixed to said clamping means adapted to open said valves when said valves are clamped in register with said conduits, and means for selectively applying to the other ends of said conduits a gaseous pressure, whereby either envelope may be filled by applying a vacuum to the other envelope, and may be emptied by applying a posi tive pressure to the other envelope.

3. In a gas-sampling system, a rigid gas-tight tubular member, a flexible gas-tight tubular member wholly within said rigid tubular member, sealing means forming a gas-tight bond between the rims of said tubular members at either end thereof, whereby an annular gas-tight space is formed between said tubular members, gas-tight means closing the open ends of said flexible tubular member, whereby a second gastight space is formed within said annular gastight space, a gas-tight chamber, a gas conduit in communication between said chamber and the annular space between the rigid and the flexible tubular members, a second gas conduit in communication between said chamber and the space within the flexible tubular member, a tube having an outer end immersed in the space from which the sample is collected and an inner end projecting into said chamber, said inner end being adapted for sealing engagement with either of the conduits opening to said chamber, an orifice through the walls of said chamber, and means for selectively filling the space on either end of said flexible envelope with a gaseous sample by connecting said tube to either of said conduits and applying a vacuum to said orifice.

GERALD L. HASSLER. 

